The invention concerns pumps for fluids generally.
The most widely used pumps for fluids are the double-acting type in which there is an alternating piston that, drawing in a fluid, simultaneously compresses the fluid drawn in during the piston's previous stroke made in the opposite direction.
These devices are usually complex and bulky because of the need for valves to permit entry of air and exit of compressed air at each stroke of the piston.
Elastic means of reaction are used to return the valves to their closed position and re-open them, in line with the action of the moving piston and create a cyclic distribution of the fluid at the desired pressure, quantities and delivery.
Especially in the nautical field where such wide use is made of inflatable rubber craft, the possibililty of rapidly inflating them with light simple and compact means is of decisive importance.
The chief advantage of having a rubber dinghy lies just in the fact of being able to turn an easily-stowed object like a deflated dinghy into a real boat, even of some considerable size.
The presently known hand-operated pumps are tiring to use; motor-driven ones are excessively bulky and expensive.